Question

Bai1 : tính hợp lí
A = 17\(\dfrac{2}{31}\) - ( \(\dfrac{15}{17}\) + 6\(\dfrac{2}{31}\) )

B = ( 31\(\dfrac{6}{13}\) + 5\(\dfrac{9}{41}\) ) - 36\(\dfrac{9}{41}\) ) - 36\(\dfrac{6}{13}\)

C = 27\(\dfrac{51}{59}\) - ( 7\(\dfrac{51}{59}\) - \(\dfrac{1}{3}\) )

bai2: Tính

A = \(\dfrac{1}{2.3}\) + \(\dfrac{1}{3.4}\) + \(\dfrac{1}{4.5}\) +...+ \(\dfrac{1}{49.50}\)

B = \(\dfrac{1}{37}\) + \(\dfrac{1}{7.11}\) + \(\dfrac{1}{11.15}\)+....+\(\dfrac{1}{23.27}\)

Answer 1

Bài 1: 

a: \(=17+\dfrac{2}{31}-\dfrac{15}{17}-6-\dfrac{2}{31}=11-\dfrac{15}{17}=\dfrac{172}{17}\)

b: \(=31+\dfrac{6}{13}+5+\dfrac{9}{41}-36-\dfrac{9}{41}-36-\dfrac{6}{13}\)

=36

c: \(=27+\dfrac{51}{59}-7-\dfrac{51}{59}+\dfrac{1}{3}=20+\dfrac{1}{3}=\dfrac{61}{3}\)